JP3637784B2 - Control device for variable valve engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control apparatus for a variable valve engine that includes a variable valve intake valve that can arbitrarily control the opening and closing timing, and controls the intake air amount by controlling the closing timing of the intake valve.
[0002]
[Prior art]
As a conventional control apparatus for a variable valve engine, as disclosed in Japanese Patent Application Laid-Open No. 59-163212, the intake valve and the exhaust valve are electromagnetically controlled to open and close, and the intake valve and exhaust valve open / close timing and lift are controlled. There is a type in which the engine output is adjusted by making the characteristics variable according to the operating state and adjusting the opening of the intake valve and the exhaust valve.
[0003]
Furthermore, in recent years, for the purpose of improving fuel efficiency by reducing pump loss, control of intake valve closing timing (premature closing control) to control the amount of intake air and perform non-throttle operation has attracted attention. Development is underway.
[0004]
[Problems to be solved by the invention]
However, when the intake valve closing timing is controlled to control the intake air amount, there is a problem that an air-fuel ratio shift occurs during acceleration / deceleration unless the fuel injection amount control is synchronized.
That is, as described in the above publication, when the intake valve closing timing is calculated based on engine operating conditions at a predetermined cycle and the fuel injection amount is calculated, the intake valve closing timing is compared with the fuel injection timing. If the intake valve closing control is controlled based on the latest calculated intake valve closing timing after fuel injection based on the latest calculated fuel injection amount at the fuel injection timing, the fuel injection Since the engine operating conditions used to calculate the amount and the engine operating conditions used to calculate the intake valve closing timing are different during acceleration / deceleration, the fuel injection amount control and the intake air amount control are different, and the deviation of the air-fuel ratio is reduced. It happens.
[0005]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and it is an object of the present invention to reliably control the fuel injection amount and the intake valve closing timing to improve the control accuracy of the air-fuel ratio.
[0006]
[Means for Solving the Problems]
For this reason, in the invention according to claim 1, as shown in FIG. 1, the fuel injection amount calculating means for calculating the fuel injection amount based on the engine operating condition, and the fuel for calculating the fuel injection timing based on the engine operating condition. An injection timing calculating means for controlling the fuel injection of the fuel injection valve, and an intake valve closing timing calculating means for calculating the intake valve closing timing based on the engine operating conditions. In the control apparatus for a variable valve engine that controls the intake air amount by controlling the closing timing of the intake valve of the formula, the calculation of the fuel injection amount by the fuel injection amount calculating means and the closing of the intake valve by the intake valve closing timing calculating means time of calculation, at a predetermined time period, while simultaneously carried out at the fuel injection timing calculating unit fuel injection timing for actual fuel injection is calculated by the fuel the fuel injection amount A fuel injection amount determining means that is determined by the latest fuel injection amount calculated by the injection amount calculating means, and simultaneously with the determination of the fuel injection amount, the intake valve closing timing is latest calculated by the intake valve closing timing calculating means. And an intake valve closing timing determining means for determining the intake valve closing timing.
[0007]
The invention according to claim 2 is characterized in that the fuel injection timing calculating means calculates the fuel injection timing simultaneously with the calculation of the fuel injection amount and the intake valve closing timing.
[0008]
The invention according to claim 3 is characterized in that the fuel injection timing is determined at the predetermined crank angle position by the fuel injection timing that is calculated latest by the fuel injection timing calculation means.
The invention according to claim 4 is characterized in that the fuel injection amount calculating means calculates the fuel injection amount based on the intake air amount measured by the intake air amount measuring means.
[0009]
The invention according to claim 5 is characterized in that the fuel injection timing calculating means calculates the fuel injection timing based on the engine speed and the fuel injection amount.
The invention according to claim 6 is characterized in that the intake valve closing timing calculating means calculates the intake valve closing timing according to a target air amount determined based on the accelerator opening and the engine speed. .
[0010]
The invention according to claim 7 is characterized in that the variable valve-type intake valve is of an electromagnetic drive type.
[0011]
【The invention's effect】
According to the first aspect of the present invention, in the variable valve engine having high responsiveness of intake air amount control by controlling the intake valve closing timing to control the intake air amount, fuel injection that actually performs fuel injection At the same time, the fuel injection amount is determined, and at the same time, the intake valve closing timing is determined, and thereafter, the intake valve closing timing is not changed by the actual intake valve closing timing. The control accuracy of the air-fuel ratio can be improved by reliably synchronizing the control and the control of the intake valve closing timing.
Further, by simultaneously calculating the fuel injection amount and the intake valve closing timing in a predetermined time period, it is possible to calculate them under completely the same engine operating conditions and to synchronize more reliably.
[0012]
According to the second aspect of the present invention, the fuel injection timing can be calculated under the same engine operating condition by calculating the fuel injection timing simultaneously with the calculation of the fuel injection amount and the intake valve closing timing.
[0013]
According to the third aspect of the present invention, the fuel injection timing can be reliably controlled by determining the fuel injection timing at the predetermined crank angle position.
According to the invention of claim 4 , the control accuracy of the air-fuel ratio can be further improved by calculating the fuel injection amount based on the measurement result of the intake air amount measuring means.
According to the fifth aspect of the present invention, the fuel injection timing can be optimized by calculating the fuel injection timing based on the engine speed and the fuel injection amount.
[0014]
According to the sixth aspect of the invention, it is possible to control the intake air amount according to the required torque by calculating the intake valve closing timing according to the target air amount determined based on the accelerator opening and the engine speed. Become.
In the invention which concerns on Claim 7 , controllability improves by using an electromagnetically driven intake valve.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to FIGS.
FIG. 2 is a system diagram of a variable valve engine showing an embodiment of the present invention.
The combustion chamber 3 defined by the piston 2 of each cylinder of the engine 1 is provided with an electromagnetically driven intake valve 5 and an exhaust valve 6 so as to surround the spark plug 4. 7 is an intake passage and 8 is an exhaust passage.
[0016]
FIG. 3 shows the basic structure of an electromagnetic drive device (variable valve operating device) for the intake valve 5 and the exhaust valve 6. A plate-like movable element 22 is attached to the valve shaft 21 of the valve body 20, and the movable element 22 is biased to a neutral position by springs 23 and 24. A valve opening electromagnetic coil 25 is disposed below the mover 22, and a valve closing electromagnetic coil 26 is disposed above the movable element 22.
[0017]
Therefore, when opening the valve, after energization of the upper valve closing electromagnetic coil 26 is stopped, by energizing the lower valve opening electromagnetic coil 25 and attracting the mover 22 downward, The valve body 20 is lifted and opened. Conversely, when closing the valve, by energizing the lower valve opening electromagnetic coil 25 and then energizing the upper valve closing electromagnetic coil 26 to attract the mover 22 upward, The valve body 20 is seated on the seat portion and closed.
[0018]
Returning to FIG. 2, the intake passage 7 is provided with an electromagnetic fuel injection valve 9 in the intake port portion of each cylinder.
Here, the operation of the intake valve 5, the exhaust valve 6, the fuel injection valve 9 and the spark plug 4 is controlled by a control unit 10, which outputs a crank angle signal in synchronism with engine rotation. From the crank angle sensor 11 capable of detecting the engine rotational speed Ne, the accelerator pedal sensor 12 for detecting the accelerator opening (accelerator pedal depression amount) APO, and the air flow meter 13 for measuring the intake air amount Qa in the intake passage 7 A signal is being input.
[0019]
In addition, signals are input from a water temperature sensor for detecting the cooling water temperature Tw, an oxygen sensor for detecting the rich / lean air-fuel ratio via the oxygen concentration in the exhaust gas, etc., but the illustration is omitted.
In the engine 1, the valve timing of the electromagnetically driven intake valve 5 and the exhaust valve 6 is controlled for the purpose of improving the fuel efficiency by reducing the pump loss, and in particular, the opening timing (IVO) of the intake valve 5 is set to the exhaust top dead center (TDC). As a substantially constant timing in the vicinity, the intake air amount is controlled by early closing control of the closing timing (IVC) to perform non-throttle operation. However, an electric throttle valve may be provided for the purpose of obtaining a negative pressure in the intake passage 7 under predetermined engine operating conditions.
[0020]
The fuel injection amount and fuel injection timing by the fuel injection valve 9 are controlled based on engine operating conditions. The fuel injection amount is basically set based on the intake air amount Qa detected by the air flow meter 13. It controls so that it may become the air fuel ratio.
The ignition timing by the spark plug 4 is controlled to the MBT or knock limit based on the engine operating conditions.
[0021]
Next, the control of the fuel injection amount and the fuel injection timing and the control of the intake air amount by the intake valve closing timing will be described in more detail with reference to flowcharts.
FIG. 4 shows a 1 ms job.
In step 1 (denoted as S1 in the figure, the same applies hereinafter), the output voltage of an air flow meter (AFM) as intake air amount measuring means is read and A / D converted.
[0022]
In step 2, the A / D conversion value is linearized based on the air flow meter output characteristic to obtain the intake air amount Qa.
In Step 3, in the case of four cylinders, it is determined whether or not the timing is every 180 ° CA. If NO, the process proceeds to Step 4, and if YES, the process proceeds to Step 5.
That is, during 180 ° CA, Qa is accumulated in step 4 (ΣQa ← ΣQa + Qa), and every 180 ° CA, the accumulated result is set as the cylinder intake air amount Qcyl in step 5 (Qcyl ← ΣQa, Qcyl is determined, ΣQa ← 0).
[0023]
In step 6, it is determined whether or not the timing is every 10 ms. If NO, the process ends. If YES (timing every 10 ms), the process proceeds to step 7. Therefore, the steps after step 7 are substantially 10 ms jobs.
In step 7, the basic fuel injection amount (basic fuel injection pulse width) Tp is calculated by multiplying the cylinder intake air amount Qcyl by a constant K # as in the following equation.
[0024]
Tp = Qcyl x K #
In step 8, the target equivalent ratio TFBYA is calculated. Specifically, as shown in the following equation, the basic target equivalent ratio KMR determined based on the engine speed Ne and the basic fuel injection amount Tp, the water temperature correction amount KTW determined from the water temperature Tw, the post-start time determined from the start time, etc. The target equivalent ratio TFBYA is calculated by adding the correction amount KAS.
[0025]
TFBYA = KMR + KTW + KAS
The target equivalent ratio TFBYA is expressed by TFBYA = 14.7 / tA / F where the target air-fuel ratio is tA / F and the theoretical air-fuel ratio is 14.7.
In step 9, a transient correction coefficient (acceleration / deceleration wall flow correction coefficient) KTR is calculated. Specifically, the intake port wall flow rate is predicted as a function of the water temperature Tw, the basic fuel injection amount Tp, and the engine speed Ne, and the fuel injection amount is increased and corrected to correct fuel shortage due to wall flow during acceleration. In the deceleration mode, the fuel injection amount is corrected so as to be reduced so as to correct the excess fuel due to the wall flow.
[0026]
In step 10, the basic fuel injection amount Tp is corrected by the target equivalent ratio TFBYA, the transient correction coefficient KTR, the air-fuel ratio feedback correction coefficient α, the learning correction coefficient αm, and the voltage correction (invalid injection time) Ts as shown in the following equation. Then, the fuel injection amount (fuel injection pulse width) Ti (ms) is calculated.
Ti = Tp × TFBYA × KTR × α × αm + Ts
Here, the steps 7 to 10 correspond to the fuel injection amount calculating means.
[0027]
In step 11, the fuel injection timing I / T is calculated. Specifically, referring to the map of FIG. 8, the fuel injection timing I / T (CA before exhaust top dead center; ° BTDC) is set from the engine speed Ne and the fuel injection amount Ti. This portion corresponds to fuel injection timing calculation means.
In step 12, the intake valve closing timing IVC is calculated according to the flow of FIG. 5 (step 21 to step 26). This portion corresponds to intake valve closing timing calculation means.
[0028]
The IVC calculation flow in FIG. 5 will be described.
In step 21, a basic target air amount TTA is calculated. Specifically, referring to the map of FIG. 9, a basic target air amount TTA corresponding to the required torque is set from the accelerator opening APO and the engine speed Ne.
In step 22, the idle air amount ISC is calculated.
[0029]
Specifically, the idle air amount ISC is the larger of the idle control amount ISCQ and the negative pressure control amount BCV as shown in the following equation.
ISC = MAX (ISCQ, BCV)
The idle control amount ISCQ is determined by the auxiliary load correction amount ISCLD determined based on the state of the auxiliary load (air conditioner, power steering, electric load, etc.), and the actual idle speed is set as the target idle speed during idle operation. The integral part ISCI and the proportional part ISCP, which are the idle speed feedback correction parts set in comparison with the above, are added and calculated.
[0030]
ISCQ = ISCLD + ISCI + ISCP
The negative pressure control BCV is set according to the engine speed Ne in order to prevent the negative pressure in the cylinder from becoming excessive due to the early closing control of the intake valve and causing the oil to rise.
In step 23, as shown in the following equation, the target air amount TTP is calculated by adding the idle air amount ISC to the basic target air amount TTA.
[0031]
TTP = TTA + ISC
In step 24, the intake valve closing timing IVCφ is calculated. Specifically, referring to the table of FIG. 10, the intake valve closing timing IVC (CA after exhaust top dead center; ° ATDC) is set from the target air amount TTP. Since the charging efficiency changes depending on the inertia of the intake air depending on the engine speed Ne, the intake valve closing timing IVC may be set from the target air amount TTP and the engine speed Ne.
[0032]
In step 25, a delay angle IVDLY is obtained by converting an operation delay time (for example, 3 ms) from the close command of the electromagnetically driven intake valve to the actual close into a crank angle.
In step 26, the intake valve closing timing (command value) IVC is obtained by subtracting the delay angle IVDLY from the intake valve closing timing IVCφ as shown in the following equation.
[0033]
IVC = IVCφ−IVDLY
The process ends as described above.
The intake valve opening timing (IVO) is set to a substantially constant timing near the exhaust top dead center (TDC). Further, the exhaust valve opening timing (EVO) and closing timing (EVC) are controlled so as to be the timing with the highest thermal efficiency.
[0034]
FIG. 6 shows a REF job that is executed in synchronization with a reference crank angle signal REF from the crank angle sensor (in the case of four cylinders, generated every 180 ° CA, for example, at 110 ° CA before exhaust top dead center).
In step 31, the latest fuel injection timing I / T calculated in the 10 ms job is set in the fuel injection timing output register I / TOUT. This part corresponds to the fuel injection timing determining means.
[0035]
As a result, when the fuel injection timing I / T is reached, output of the fuel injection pulse signal to the fuel injection valve is started, and fuel injection is started.
In the REF job, in step 32, the air-fuel ratio feedback correction coefficient α for air-fuel ratio feedback control is calculated based on the signal from the oxygen sensor. In step 33, the learning correction coefficient αm for air-fuel ratio learning control is calculated by learning the steady-state deviation of the air-fuel ratio feedback correction coefficient α.
[0036]
FIG. 7 shows an I / T interrupt job that is interrupted at the actual fuel injection timing I / T.
In step 41, the latest fuel injection amount (fuel injection pulse width) Ti calculated in the 10 ms job is set in the fuel injection amount (fuel injection pulse width) output register TiOUT. This portion corresponds to the fuel injection amount determining means.
[0037]
Thereby, when Ti time passes after fuel injection start, the output of the fuel injection pulse signal to a fuel injection valve will be stopped, and fuel injection will be complete | finished.
In step 42, the latest intake valve closing timing (command value) IVC calculated in the 10 ms job is set in the intake valve closing timing output register IVCOUT. This portion corresponds to intake valve closing timing determination means.
[0038]
Thus, when the intake valve closing timing IVC is reached, energization of the valve opening electromagnetic coil is stopped, and energization of the valve closing electromagnetic coil is started to close the intake valve.
FIG. 11 is a timing chart for a certain cylinder.
The fuel injection amount Ti, the fuel injection timing I / T, and the intake valve closing timing IVC are calculated every predetermined time period, that is, every 10 ms.
[0039]
Here, in synchronism with a predetermined crank angle position, that is, a reference crank angle signal REF of 110 ° CA before exhaust top dead center, the fuel injection timing I / T is calculated as the latest fuel injection timing I at this time. Confirm with / T.
When the determined fuel injection timing I / T is reached, the fuel injection amount Ti is determined by the latest fuel injection amount Ti calculated at this time, and at the same time, the intake valve closing timing IVC is calculated the latest. Determined by the intake valve closing timing IVC. In other words, thereafter, even if the intake valve closing timing IVC is newly calculated before the actual intake valve closing timing IVC, the intake valve closing timing IVC is not changed.
[0040]
Therefore, the control of the fuel injection amount Ti and the control of the intake valve closing timing IVC can be surely synchronized to improve the control accuracy of the air-fuel ratio.
In the above embodiment, an electromagnetically driven type is used as the variable valve operating device, but a hydraulically driven type may be used.
[Brief description of the drawings]
1 is a functional block diagram showing the configuration of the present invention. FIG. 2 is a system diagram of a variable valve engine showing an embodiment of the present invention. FIG. 3 is a basic structural diagram of an electromagnetic drive device for intake and exhaust valves. Flowchart of 1ms job (and 10ms job) [Fig.5] Flowchart of IVC calculation [Fig.6] Flowchart of REF job [Fig.7] Flowchart of I / T interrupt job [Fig.8] Diagram showing I / T setting map FIG. 9 is a diagram showing a TTA setting map. FIG. 10 is a diagram showing an IVC setting table. FIG. 11 is a timing chart for a certain cylinder.
DESCRIPTION OF SYMBOLS 1 Engine 4 Spark plug 5 Electromagnetically driven intake valve 6 Electromagnetically driven exhaust valve 9 Fuel injection valve 10 Control unit 11 Crank angle sensor 12 Accelerator pedal sensor 13 Air flow meter

Claims (7)

A fuel injection amount calculating means for calculating the fuel injection amount based on the engine operating condition; and a fuel injection timing calculating means for calculating the fuel injection timing based on the engine operating condition. While controlling
An intake valve closing timing calculating means for calculating an intake valve closing timing based on engine operating conditions is provided, and thereby a variable valve engine for controlling an intake air amount by controlling a closing timing of a variable valve type intake valve. In the control device,
While the calculation of the fuel injection amount by the fuel injection amount calculating means and the calculation of the intake valve closing timing by the intake valve closing timing calculating means are performed simultaneously in a predetermined time period,
Fuel injection amount determining means for determining the fuel injection amount based on the latest fuel injection amount calculated by the fuel injection amount calculating means at the fuel injection timing calculated by the fuel injection timing calculating means and actually performing fuel injection. When,
And an intake valve closing timing determining means for determining the intake valve closing timing based on the latest intake valve closing timing calculated by the intake valve closing timing calculating means simultaneously with the determination of the fuel injection amount. Control device for variable valve engine. 2. The control apparatus for a variable valve engine according to claim 1, wherein the fuel injection timing calculation means calculates the fuel injection timing simultaneously with the calculation of the fuel injection amount and the intake valve closing timing. The variable valve operating system according to claim 1 or 2 , wherein the fuel injection timing is determined at a predetermined crank angle position based on a fuel injection timing that is latest calculated by the fuel injection timing calculation means. Engine control device. The fuel injection amount calculating means, to any one of claims 1 to 3, characterized in that for calculating the fuel injection amount based on the intake air amount measured by the intake air quantity measuring means The control apparatus of the variable valve engine described. 5. The variable valve operating system according to claim 1, wherein the fuel injection timing calculation means calculates a fuel injection timing based on an engine speed and a fuel injection amount. Engine control device. 6. The intake valve closing timing calculating means according to claim 1, wherein the intake valve closing timing calculating means calculates an intake valve closing timing according to a target air amount determined based on an accelerator opening and an engine speed. The control apparatus for a variable valve engine according to any one of the above. The control apparatus for a variable valve engine according to any one of claims 1 to 6 , wherein the variable valve intake valve is an electromagnetic drive type.

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